Evidence for distinct genetic and environmental influences on fear acquisition and extinction

Background Anxiety disorders are highly prevalent with an early age of onset. Understanding the aetiology of disorder emergence and recovery is important for establishing preventative measures and optimising treatment. Experimental approaches can serve as a useful model for disorder and recovery relevant processes. One such model is fear conditioning. We conducted a remote fear conditioning paradigm in monozygotic and dizygotic twins to determine the degree and extent of overlap between genetic and environmental influences on fear acquisition and extinction. Methods In total, 1937 twins aged 22–25 years, including 538 complete pairs from the Twins Early Development Study took part in a fear conditioning experiment delivered remotely via the Fear Learning and Anxiety Response (FLARe) smartphone app. In the fear acquisition phase, participants were exposed to two neutral shape stimuli, one of which was repeatedly paired with a loud aversive noise, while the other was never paired with anything aversive. In the extinction phase, the shapes were repeatedly presented again, this time without the aversive noise. Outcomes were participant ratings of how much they expected the aversive noise to occur when they saw either shape, throughout each phase. Results Twin analyses indicated a significant contribution of genetic effects to the initial acquisition and consolidation of fear, and the extinction of fear (15, 30 and 15%, respectively) with the remainder of variance due to the non-shared environment. Multivariate analyses revealed that the development of fear and fear extinction show moderate genetic overlap (genetic correlations 0.4–0.5). Conclusions Fear acquisition and extinction are heritable, and share some, but not all of the same genetic influences.

An attentional perspective on differential fear conditioning in chronic pain: The informational value of safety cues.

Differences in fear conditioning between individuals suffering from chronic pain and healthy controls may indicate a learning bias that contributes to the acquisition and persistence of chronic pain. However, evidence from lab-controlled conditioning studies is sparse and previous experiments have produced inconsistent findings. Twenty-five participants suffering from chronic back pain and twenty-five controls not reporting chronic pain took part in a differential fear conditioning experiment measuring attention (eye tracking) and autonomic arousal (pupil dilation and skin conductance) elicited by visual cues predicting the presence or absence of electric shock. In contrast to the healthy control group, participants with chronic pain did not acquire differential autonomic responding to cues of threat and safety and specifically failed to acquire any attentional preference for the safety cue over irrelevant contextual cues (while such preference was intact for the threat cue). We present simulations of a reinforcement learning model to show how the pattern of data can be explained by assuming that participants with chronic pain might have experienced less positive emotion (relief) when the electric shock was absent following safety cues. Our model shows how this assumption can explain both, reduced differential responding to cues of threat and safety as well as less selective attention to the safety cue.

Evidence for distinct genetic and environmental influences on fear acquisition and extinction

BackgroundAnxiety disorders are highly prevalent with an early age of onset. Understanding the aetiology of disorder emergence and recovery is important for establishing preventative measures and optimising treatment. Experimental approaches can serve as a useful model for disorder and recovery relevant processes. One such model is fear conditioning. We conducted a remote fear conditioning paradigm in monozygotic and dizygotic twins to determine the degree and extent of overlap between genetic and environmental influences on fear acquisition and extinction.Methods1937 twins aged 22-25 years, including 538 complete pairs from the Twins Early Development Study (TEDS) took part in a fear conditioning experiment delivered remotely via the Fear Learning and Anxiety Response (FLARe) smartphone app.In the fear acquisition phase participants were exposed to two neutral shape stimuli, one of which was repeatedly paired with a loud aversive noise, while the other was never paired with anything aversive. In the extinction phase the shapes were repeatedly presented again, this time without the aversive noise. Outcomes were participant ratings of how much they expected the aversive noise to occur when they saw either shape, throughout each phase.ResultsTwin analyses indicated a significant contribution of genetic effects to the initial acquisition and consolidation of fear, and the extinction of fear (15%, 30% and 15% respectively) with the remainder of variance due to the non-shared environment. Multivariate analyses revealed that the development of fear and fear extinction show moderate genetic overlap (genetic correlations .4-.5).ConclusionsFear acquisition and extinction are heritable, and share some, but not all of the same genetic influences.

A Photoelectric-Stimulated MoS2 Transistor for Neuromorphic Engineering

The von Neumann bottleneck has spawned the rapid expansion of neuromorphic engineering and brain-like networks. Synapses serve as bridges for information transmission and connection in the biological nervous system. The direct implementation of neural networks may depend on novel materials and devices that mimic natural neuronal and synaptic behavior. By exploiting the interfacial effects between MoS2 and AlOx, we demonstrate that an h-BN-encapsulated MoS2 artificial synapse transistor can mimic the basic synaptic behaviors, including EPSC, PPF, LTP, and LTD. Efficient optoelectronic spikes enable simulation of synaptic gain, frequency, and weight plasticity. The Pavlov classical conditioning experiment was successfully simulated by electrical tuning, showing associated learning behavior. In addition, h-BN encapsulation effectively improves the environmental time stability of our devices. Our h-BN-encapsulated MoS2 artificial synapse provides a new paradigm for hardware implementation of neuromorphic engineering.

Efecto del acondicionamiento osmótico con soluciones de KNO3 en la germinación de semillas de Amaranthus hypochondriacus L.

Amaranth can help to decrease the problems of food, malnutrition and health of the human population, as it provides energy, protein, vitamins and minerals and is also a natural source of lysine, a rare amino acid in other cereals. However, when stored for use as seeds, they suffer a relatively rapid deterioration, which is mainly reflected in low germination. Osmotic conditioning or "priming" is a treatment that can improve the germination capacity of the seeds, once they have been subjected to deterioration. In this work, an osmotic conditioning experiment was carried out with the objective of increasing the germination percentage in amaranth seeds accessions that are conserved at the National Center of Genetic Resources (CNRG) of INIFAP. The seeds of four amaranth genotypes were hydrated in five KNO3 solutions for 2 h, followed by a 24 h drying period at 25 °C. Subsequently, these seeds were tested for germination. The results showed that the germination was increased with osmotic conditioning using KNO3 solutions, thereby the seed deterioration was reverted. Also, the genotype had an effect on the germinative behavior of the seeds.

Negative evidence and inductive reasoning in generalization of associative learning

When generalizing properties from known to novel instances, both positive evidence (instances known to possess a property) and negative evidence (instances known not to possess a property) must be integrated. The current study compared generalization based on positive evidence alone against a mixture of positive evidence and perceptually dissimilar negative evidence in an interdimensional discrimination procedure. In 2 experiments, we compared generalization following training with a single positive stimulus (that predicted shock) against groups where an additional negative stimulus (that did not predict shock) was presented in a causal judgment (Experiment 1) and a fear conditioning (Experiment 2) procedure. In contrast to animal conditioning studies, we found that adding a “distant” negative stimulus resulted in an overall increase in generalization to stimuli varying on the dimension of the positive stimulus, consistent with the inductive reasoning literature. We show that this key qualitative result can be simulated by a Bayesian model that incorporates helpful sampling assumptions. Our results suggest that similar processes underlie generalization in inductive reasoning and associative learning tasks.

Validating the Use of a Smartphone App for Remote Administration of a Fear Conditioning Paradigm

Fear conditioning models key processes related to the development, maintenance and treatment of anxiety disorders and is associated with group differences in anxiety. However, laboratory administration of tasks is time and cost intensive, precluding assessment in large samples, necessary for analysis of individual differences. This study introduces a newly developed smartphone app that delivers a fear conditioning paradigm remotely. Three groups of participants (total n=152) took part in three studies involving a differential fear conditioning experiment to assess the reliability and validity of a smartphone administered fear conditioning paradigm. This comprised of fear acquisition, generalisation, extinction, and renewal phases. We show that smartphone app delivery of a fear conditioning paradigm results in a pattern of fear learning comparable to traditional laboratory delivery, and is able to detect individual differences in performance that show comparable associations with anxiety to the prior group differences literature.

Explorations with Conditioned Stimuli in Autoshaping Procedures

Sign-tracking is a form of autoshaping where by animals reliably develop conditioned responses toward stimuli that predict an outcome. While the assignment of some value to a predictive cue may be adaptive (i.e., to be alerted to food and water sources), the attribution of value to predictive cues can be maladaptive as seen in behaviors elicited during addiction. Here we test if responding to the predictive cue changes in the context of other cues that are only partially predictive (Experiment 1). Previous work on sequential cues leading to reward have shown a bias in responding toward the first cue in the sequence over learning (Smedley and Smith 2018a, 2018b). Here we test if this effect is unique to discrete cues or if a bias in responding can be seen in a single, long cue (Experiment 2). Finally, we investigate if sign-tracking responses can reliably develop towards a cue that arrives after the delivery of reward (backwards conditioning, Experiment 3). Together, we aim to address various gaps in knowledge about the nature of the sign-tracking response.

Using Episodic Future Thinking to Pre-Experience Climate Change Increases Pro-Environmental Behavior

Research has found that many people view climate change as a psychologically distant, future threat, which leads them to be less motivated to engage in pro-environmental behavior. Engaging in episodic future thinking (EFT; projecting the self into the future to pre-experience future events) may facilitate the perception of future events as psychologically close, thereby increasing the perceived risk associated with those events. Therefore, engagement in EFT regarding climate change–related risks should induce higher risk perceptions and lead to acting pro-environmentally. In two experiments, we demonstrated that engaging in EFT to pre-experience climate change–related risk events was associated with a higher level of risk perception and a greater tendency toward pro-environmental behavior, including energy-saving use of air-conditioning (Experiment 1), willingness to participate in beach cleaning (Experiment 2), and choice of a meal with lower environmental impact (Experiment 2). The current research provides experimental evidence for an innovative approach to improving public engagement with climate change.